The present invention relates to a vehicular power distribution system which distributes power from a main power source to a plurality of systems in a vehicle and then supplies the power, thus distributed to the plurality of systems, to respective electric devices via predetermined wire harnesses.
In a vehicle, various electric devices are disposed in a dispersed manner at various portions in a vehicle body. For example, electric devices relating to running of a vehicle, electric devices relating to an audio system, electric devices relating to functions of the vehicle body and so on are disposed at various portions such as a steering column, a glove box, a center cluster and a center console. Usually, each of such the electric devices mounts various switches, various sensors, various loads, control relays and so on.
Such the various electric devices are required to be supplied with power from a main power supply (an on-vehicle battery or an alternator) on the vehicle side. Further, signals from the switches and the sensors provided in some of the electric devices are required to be transmitted to others of the electric devices and various electronic control units (ECUs) provided in the vehicle.
To this end, conventionally, the power source on the vehicle side is connected to the various electric devices and the various electronic control units via wire harnesses. In general, each of such the wire harnesses is configured by binding many wires. Further, a length of each of the wires is adjusted and a shape of each of the wire harnesses is determined in accordance with positional relations of the electric devices so that the devices disposed at respective portions can be mutually connected surely. Further, a thickness of each of the wires for power supply constituting each of the wire harnesses is determined depending on a magnitude of power consumed by a load of corresponding one of the electric devices. Furthermore, a connector is coupled to an end portion of each of wire bundles constituting the wire harness so that the wire harness can be electrically and detachably connected to corresponding electric devices with ease.
Recently, in most cases, many electronic control units (ECUs) are mounted at various portions in a vehicle. Thus, the many electronic control units are required to be connected via communication lines contained in wire harnesses so that the many electronic control units can communicate to each other. In this case, if the number of the electronic control units etc. mounted in a vehicle increases, a size of each of the wire harnesses becomes large. As a result, it becomes difficult to secure a space for disposing the wire harnesses and further a weight of the wire harnesses increases.
In a vehicular power distribution system disclosed in a patent literature 1, a plurality of electric connection boxes are provided in order to distribute power of a power source. Each of the electric connection boxes contains many fuses and relays.
In an on-vehicle system disclosed in a patent literature 2, when a supply side of power of a power source receives a power supply request to a load, propriety of the power supply is determined based on a state of the power source and a power supply amount to the load. By doing so, a residual amount of the power source can be prevented from reducing below a minimum required value.
In a power source circuit for a vehicle disclosed in a patent literature 3, a power line is separated into a plurality of systems based on characteristics of a plurality of loads connected thereto, and a noise protection circuit is commonly provided for each the system.
In a power supplying device for a vehicle disclosed in a patent literature 4, a shutdown circuit and an inrush current limiting circuit are provided between a power supplying side and each of loads (ECU).
In an electronic control system for a vehicle disclosed in a patent literature 5, a plurality of shared I/O units are connected to a single electronic control device via communication lines and power source lines, and a non-shared I/O unit is connected to the electronic control device as needed. Further, the single electronic control device mounts control softwares for all electric devices.
In a power source circuit for a vehicle and an electric connection box for a vehicle disclosed in a patent literature 6, a noise filter is connected to each of power lines connecting between a power source and respective loads.    [Patent Literature 1] JP-A-2004-56944    [Patent Literature 2] JP-A-2008-49982    [Patent Literature 3] JP-A-2011-105205    [Patent Literature 4] JP-A-2011-213321    [Patent Literature 5] JP-A-2012-76630    [Patent Literature 6] JP-A-2013-166513